Dehydrogenation catalysts

ABSTRACT

BERYLLIUM CHROMITES, ESPECIALLY THOSE PROMOTED WITH ALUMINUM, HAVE BEEN FOUND TO BE COMPARABLE TO CHROMIA-ALUMINA TYPE DEHYDROGENATION CATALYSTS, FOR EXAMPLE, IN THE DEHYDROGENATION OF N-BUTANE. THE ALUMINUM IS EITHER ADDED TO THE PREFORMED BERYLLIUM CHROMITE OR IS INCOPORATED INTO THE SPINEL STRUCTURE OF THE CHROMITE ITSELF OR ADDED IN BOTH WAYS. THE ALUMINUM CAN BE PRESENT IN THE CATALYST FROM ALL SOURCES IN AN ATOMIC RATIO OF A1:CR OF 0.0004 TO 1.2:1. THE ATOMIC RATIO WILL MORE USUALLY BE 0.04 TO 0.8:1, A1:CR.

United States Patent 3,767,596 DEHYDROGENATION CATALYSTS Harold E. Manning, Houston, Tex., assignor to Petro- Tex Chemical Corporation, Houston, Tex. N0 Drawing. Filed Sept. 9, 1971, Ser. No. 179,221 Int. Cl. 501i 11/06, 11/08, 11/32 U.S. Cl. 252-465 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for the dehydrogenation of gaseous hydrocarbons and the catalyst employed. More specifically the process is a cyclic process wherein there are alternating cycles of dehydrogenation and catalyst regeneration.

The process is a cyclic process in which gaseous hydrocarbons such as butane or isopentane are dehydrogenated over a suitable catalyst to produce butenes and butadiene and isopentene and isoprene respectively. After each dehydrogenation cycle there is a catalyst regeneration cycle in which the accumulated coke is burned off by passing molecular oxygen through the catalyst followed by another dehydrogenation cycle and so on.

The chromia-alumina catalyst have been recognized for a number of years as the most preferred catalyst for this type of process. The chromia-alumina catalysts are prepared by treating activated alumina with a solution of chromic acid, draining off the excess acid from the alumina, drying and heat treating at about 1400 F. Commercial chromia-alumina dehydrogenation catalysts normally contain about 20% chromium oxide. Preparative methods are shown, for example, in U.S. Pats. 2,399,678 and 2,419,997.

Other chromia-metal oxide materials have been investigated for their dehydrogenation capabilities. One of the more prominent among these has been chromia-magnesia which has been found to be a poor second to chromia-alumina. Other catalysts have been suggested, such as chromia-alumina and magnesia-alumina promoted with beryllium oxide dehydrogenation catalysts, e.g., U.S. 2,325,911; 2,393,537; 2,483,929; 2,518,714 and 2,536,085.

It is an object of the present invention to find an alternative catalyst to chromia-alumina for use in cyclic dehydrogenation processes. It is still a further object to provide a process which will give comparable results to those presently achieved with chromia-alumina catalysts. Other objects and advantages of the present invention will be apparent from the following description.

DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS The objects of the present invention have been achieved by use of a novel catalyst containing chromium, beryllium and oxygen. The catalysts are characterized as beryllium chromites. Chromites generally have a spinel structure. This can be attributed to the octahedral site preference energy of Cr which is the greatest of all cations which can form spinel-type structures. The crystal structure of the beryllium chromites will usually be a face centered orthorhombic form.

"ice

The catalysts of the present invention are predominately chromites, that is, they contain more than 50% by weight of the chromite. Preferably the catalysts contain or more chromites, i.e., chromites. The chromites generally may be represented by the formula MeCr O where Me as stated above is Be, however, a portion of the beryllium can be replaced with other metals having an ionic radius approximately between about 0.5 and 1.1 A., preferably between about 0.6 and 1.0 A. In the case of such mixed chromites, Be will be the predominant Me ion, comprising at least 50 atomic percent of the Me ions present. In addition to be the Me may be one or more of the divalent ions of Mg, Ca, Sr, Ba, Fe, Mn, Co, Ni, Cu, Zn or Cd. Ions having a valence of other than +2 can also be substituted for a portion of the Me lOIlS.

In a preferred embodiment the catalyst can be described as one containing chromium, beryllium, aluminum and oxygen. These catalyst are characterized as beryllium chromites either in admixture with aluminum oxide or containing aluminum therein and can be considered as aluminum promoted beryllium chromites.

The aluminum component of the catalyst may be present as a constituent of the chromite, however, it is not necessary that the aluminum be a portion of the chromite and may be present in addition to the metal chromite in the form of aluminum oxide. The aluminum can be incorporated into the chromite by backing out a portion of the chromium. Aluminum can be substituted for up to 40% of the chromium atoms of the chromite. Such chromites have the formula MeAl Cr O where Me has the designation previously given and x is a number of from more than 0 up to 0.8.

The beryllium chromites of the present invention exhibit a certain type of X-ray diffraction pattern. The peaks observed in the X-ray diffraction pattern may not have sharp peaks such as those found, e.g., in highly crystalline material of the same chemical composition, but can and do frequently exhibit relatively broad reflection peaks. The degree of sharpness of the reflection peak may be measured by the reflection peak band width at half height (W./h./ 2). In other words, the width of the reflection peak as measured at one-half of the distance to the top of the peak is the band width at half height. The band width at half height is measured in units of 2 theta. Techniques for measuring the band widths are discussed, e.g., in chapter 9 of Klug and Alexander, X-Ray Diffraction Procedures, John Wiley and Son, New York, 1954. The observed band widths at half height of the preferred compositions of this invention are at least 0.20 2 theta and normally will be at least 0.36 2 theta. 1 The particular reflection peak used to measure the band width at one-half height is the reflection peak having Miller (hkl) indices of 101. (See, e.g., chapter of Klug and Alexander, ibid.) This description is not to be taken as a limitation of the invention in regard to the relationship between composition activity and band width.

A suitable catalyst according to this invention is beryllium chromite having X-ray diffraction peaks within the d-spacings 4.10-4.15, 3.32-3.35, 2.64-2.66, 2.43-2.46,

The powder diffraction patterns may be made, e.g., with a Norelco constant potential diffraction unit type No. 12215/0, equipped with a wide range goniometer type No. 42273/0, co per tube type No. 32147, proportional counter type No. 57250/1; all coupled to the Norelco circuit panel type No. 12206/53. The copper K alpha radiation is supplied by operating the tube at a constant potential of 40 kilOvolts and a current of 35 milliamperes. A nickel filter is used to remove K beta radiation. The detector voltage is 1600 volts and the pulse height analyzer is set to accept pulses with amplitudes between 10 and 30 volts only. Slits used are divergence 1, receiving .006 inch and scatter 1. Strip chart recordings for identification are made with a scanning speed of 1 per minute, time constant of 1 second and a full scale at 10 counts per second. No correction is made for Ka doublet or instrumental broadening of the band widths.

3 2.39-2.41, 2.32-2.35, 2.14-2.17, 1.92-1.95, 1.70-1.73, 1.65-1.68, 1.51-1.53, 1.40-1.42 and the most intense peaks between 3.32-3.35.

Chromite formation can be accomplished by reacting an active compound of chromium with an active compound of beryllium and the other designated metals. By active compound is meant a compound which is reactive under the conditions to form the chromite. Starting compounds of chromium, beryllium or the other metals may be such as the nitrates, hydroxides, hydrates, oxalates, carbonates, acetates, formates, halides, oxides, etc.

The catalyst may contain an excess of chromium over the stoichiometric amount, which is 2 atoms of chromium per atom of Me, viz (MeCr O There may be from 10 to 200 percent excess of the chromium. Similarly the Me portion of the chromite may be present in more than a stoichiometric amount.

The beryllium chromite can be prepared by precipitation, dry or wet milling or mixing, by precipitation of one of the ingredients in the presence of the other, coprecipitation and impregnation of one or more of the solid ingredients with aqueous or non-aqueous solutions of salts of the ingredients.

One particularly useful method of preparing the beryllium chromites has been by coprecipitation from an aqueous solution. Soluble metal salts of chromium, beryllium and any other metal component as described above are dissolved in water and an insoluble precipitate formed by the use of a precipitating agent.

Soluble metal salts are known for essentially all metals. In specific regard to the metal components of the present invention the following soluble metal compounds are illustrative: chromium (HI) nitrate, beryllium fluoride, magnesium chloride, calcium sulfate, strontium tetrasulfide tetrahydrate, barium trisulfide, iron (11) nitrate, manganese (II) dithionate, cobalt (II) acetate, nickel nitrate, copper nitrate, zinc sulfate, cadmium sulfate and aluminum sulfate. The precipitating agent in any compound which when reacted with the metal ion portion of the catalyst forms an insoluble compound which can be converted to the chromite. The alkali and alkaline earth hydroxides such as NaOH, KOH, CaOH, as well as ammonium hydroxide cause the precipitation of the metal hydroxides which are converted on heating to the chromites. After the precipitate is Washed and dried it is calcined to form the chromite.

The formation of the chromite is obtained by heating the precipitates or other intimate mixture of chromite precursors at an elevated temperature, e.g., 400-1100 C. (generally no greater than 1300" C.), in a controlled atmosphere, i.e., air, nitrogen, helium, a reducing atmosphere such as hydrogen, carbon monoxide or the like, for a sufiicient time, i.e., usually 5 minutes to 4 hours. A calcination temperature of 550-800 C. has been found particularly useful and temperatures in the range of 600-750 C. have been found to produce excellent catalysts. Catalysts prepared at 900-1100 C. have also been found to be highly desirable.

The aluminum component of the catalyst as stated above can be added prior to and/ or after the calcination and formation of the chromite. The aluminum component is conveniently added to the chromite as a soluble salt in a slurry with the chromite after which it is dried then decomposed by heating to aluminum oxide. Alternatively insoluble aluminum oxide can be added to the beryllium chromite, preferably in a highly divided state. Yet another desirable way to place the aluminum in the catalyst is by coprecipitation of aluminum hydroxide with the Me hydroxide and chromium hydroxide.

The aluminum can be present in the catalyst in all forms in an atomic ratio of AlzCr of 0.0004 to 1.211. For example, in terms of a soluble aluminum compound such as aluminum sulfate, added to the beryllium chromite, this would represent from about 0.09 to 70 weight percent Al (SO -l6I-I O based on the total weight of the catalyst. A more preferred range of AllCr atom ratio is .04 to 08:1. Generally the higher weight percentages of aluminum compound, i.e., 50 weight percent or more, are applied to the beryllium chromites having high surface areas, e.g., 50 m? per gram or more.

The active catalysts can be pelleted or applied to a suitable support, such as alumina, silica gel, silica-alumina, firebrick, kieselguhr, quartz and the like. The catalyst is the active surface available for contact with the gaseous reactants.

The catalysts of this invention can be applied to the dehydrogenation of a wide variety of organic compounds. Such compounds normally will contain from 2 to 20 carbon atoms, at least one l l grouping, having a boiling point below about 350 C., and may contain other elements, in addition to carbon and hydrogen such as oxygen, halogens, nitrogen and sulfur. Preferred are compounds having 2 to 12 carbon atoms, and especially preferred are compounds of 3 to 5 carbon atoms.

Representative materials which are dehydrogenated by the novel process of this invention include n-butane, ethyl toluene, alkyl chlorobenzenes, ethyl naphthalene, isobutyronitrile, propyl chloride, isobutyl chloride, ethyl fluoride, ethyl bromide, n-pentyl iodide, ethyl dichloride, 1,3-dichlorobutane, 1,4-dichlorobutane, the chlorofiuoroethanes, methyl pentane, methylethyl ketone, diethyl ketone, n-butyl alcohol, methyl propionate, and the like.

Among the types of organic compounds which may be dehydrogenated by means of the process of this invention are nitriles, amines, alkyl halides, ethers, esters, aldehydes, ketones, alcohols, acids, alkyl aromatic compounds, alkyl heterocyclic compounds, cycloalkanes, alkanes, alkenes and the like.

Suitable dehydrogenation reactions are the following: acyclic compounds having 4 to 5 non-quaternary contiguous carbon atoms to the corresponding olefins, diolefins or acetylenes having the same number of carbon atoms; aliphatic hydrocarbons having 6 to 16 carbon atoms, and at least one quaternary carbon atom to aromatic compounds, such as 2,4,4-trimethylpentene-1 to a mixture of xylenes; acyclic compounds having 6 to 16 carbon atoms and no quaternary carbon atoms to aromatic compounds such as n-hexenes to benzene; cycloparafiins and cycloolefins having 5 to 8 carbon atoms to the corresponding olefin, diolefin or aromatic compound, e.g., cyclohexane to cyclohexene or cyclohexadiene or benzene; aromatic compounds having 8 to 12 carbon atoms including one or two alkyl side chains of 2 to 3 carbon atoms to the corresponding aromatic with unsaturated side chain such as ethyl benzene to styrene.

Illustration of dehydrogenations include butane to butenes and butadiene propionitrile to acrylonitrile; propionaldehyde to acrolein; ethyl chloride to vinyl chloride; methyl isobutyrate to mentyl methacylate; 2 or 3-chlorobutene-l or 2,3-dichlorobutane to chloroprene; ethyl pyridine to vinyl pyridine; ethylbenzene to styrene; isopropylbenzene to cit-methyl styrene; ethylchlorohexane to styrene; cyclohexane to benzene; ethane to ethylene to acetylene; propane to propylene or methyl acetylene, allene, or benzene; isobutane to isobutylene; n-butane to butene and butadiene-1,3; n-butene to butadiene-l,3 and vinyl acetylene; methyl butene to isoprene; cyclopentane to cyclopentene and cyclopentadiene-l,3; n-octane to ethyl benzene and ortho-xylene; monomethylheptanes to xylenes; ethyl acetate to vinyl acetate; 2,4,4-trimethylpentane to xylenes; and the like.

The preferred compounds to be dehydrogenated are hydrocarbons with a particularly preferred class being acyclic non-quaternary hydrocarbons having 3 to 5 carbon atoms or ethyl benzene and the preferred products are propene, n-butene-l or 2, butadiene-l,3, vinyl acetylene, Z-methyl-l-butene, 3-methyl-1-butene, 3-methyl-2- butene, isoprene, styrene or mixtures thereof. Especially preferred as feed are n-butene-l or 2 and the methyl butenes and mixtures thereof such as hydrocarbon mixtures containing these compounds in at least 50 mol percent.

The dehydrogenation reaction may be carried out at atmospheric pressure, superatmospheric pressure or at sub-atmospheric pressure. The total pressure of the system will normally be about atmospheric pressure or subatmospheric pressure. Generally the total pressure will be between about 1 p.s.i.a. and about 75 p.s.i.a. Preferably the total pressure will be less than about 50 p.s.i.a.

The temperature of the dehydrogenation reaction will generally be in a range of about 350 to 700 C. with excellent results being obtained in the range of 400 to 650 C. The gaseous reactants can be conducted through the reaction chamber at a fairly wide range of flow rates. The optimum flow rates will be dependent upon such variables as the temperature of reaction, pressure, particle size of the catalyst, and so forth. Desirable flow rates may be established by one skilled in the art. Generally the flow rates will be within the range of about 0.10 to liquid volumes of the organic compound to be hydrogenated per volume of dehydrogenation zone containing catalyst per hour (referred to as LHSV). Usually the LHSV will be between 0.15 and about 5. For calculation, the volume of a fixed bed dehydrogenation Zone containing catalyst is that original void volume of reactor space containing catalyst.

The dehydrogenation is carried out in a series of cycles which comprise dehydrogenation of a suitable feed over the catalysts of the invention under the conditions as de- '6 used, i.e., isothermal atmospheric and isothermal vacuum. The absolute numbers of the results vary between the reactors because of the different conditions, however, the trends, results and relative differences in catalysts types are comparable. The presence of the chromite structure was established for the catalysts by X-ray analysis as described previously. In the examples percents are by weight except that results are given as mole percents. Analysis of the products was by gas-liquid chromatography.

EXAMPLE 1 The coprecipitated catalysts were prepared by the same method. In each instance CrCl -6H O and BeCl were dissolved in demineralized water with about 1.4% dextran 2 to produce an atom ratio of Be/Cr of 1/2 unless specified otherwise. This solution was then added to concentrated NH OH, the precipitate filtered, washed and dried at 160 C. then passed through an 80 mesh screen and calcined for 1 hour at the indicated temperature in air (unless specified otherwise) and run through a hammer mill. The soluble salts, e.g., Al (SO -16H O, were added by dissolving the salt in water, forming a slurry with the chromite (or in some cases the comparatiye commercial catalyst) and heating the slurry to dryness in a mechanical tumbler to obtain even distribution of the soluble salts. The same procedure was used to deposit the actives on a support.

heating mantle and appropriate equipment. A cc. bed of catalyst was placed in the reactor and reactant feed TABLE I [Conditionsz LHSV=1.0,Tm=-600 0. Reaction Cyele=9 minutes reaction/9 minutes regeneration] Results, mole percent Partial pressure Total S Y n-C; hrs. on Example Catalyst (atm.) stream C Bu Bd B Bd 2 Harshaw' Cr0211, 5/32 diameter pellets 1.0 24 69 65 5 4 0.33 26 67 10 46 7 3 Houdry C, 1/8 extrusions. 1.0 24 77 64 3 4 7 0. 33 26 79 16 50. 6 13 BeorgOi 1.0 24 38 54 s 20 3 0. 33 26 31 53 15 16 5 5 BeCmOr W. 1.0 24 44 67 3 29 3, 5 0.33 26 39 63 16 25 6 6 BeCrzO 1 2 5 20 wt. percent A12(S04)3.18H20 1. 0 24. 54 65 13 35 7 0.33 26 48 65 23 31 11 7 BeCrzO; 1 2 19 wt. percent Al2(S04)a.18H20 1. 0 24 64 72 7 46 4 5 0. 33 26 62 74 13 46 8 8 BeCr Or 1 4 19 wt. percent Alz(SO4)3.18H2O 1. 0 24 63 9 47 6 0. 33 26 60 73 16 44 10 9 5 32 pellets, BeCnO; 26 wt. percent A12(SO4)3.18H2O 1. 0 24 66 62 11 41 7 0.33 26 64 59 18 38 11 1 Coprecipitate of Cr/Be=2/1 calcined at 600 C. for 1 hour in air. 5 C=conversion. S=selectivity. Y=yield. Bu=butenes. Bd=

2 Catalyst is 6-8 mesh particles of 55% actives deposited on 7-9 mesh. HCl leached AMC alumina.

4 Coprecipitate 0i Cr/Be 1/1 calcined at 600 C. for 1 hour in air.

fined for a period of time, usually about 6 to 12 minutes followed by a regeneration cycle during which the coke deposited from the dehydrogenation is burnt off. The regeneration can be longer or shorter than the dehydrogenation cycle as needed to remove the coke, usually about 6 to 12 minutes will be sufiicient. The coke is removed by passing oxygen at a temperature of 550 to 650 C. over the catalyst. A convenient source of oxygen is air, however, pure oxygen or a mixture of oxygen with inert gases, such as nitrogen, either in the same or different proportions as air, can be used.

The following examples are submitted to demonstrate the operation of the invention. Two types of reactors were butadiene.

' 50% actives instead of 55%. 7 The Harshaw Chemical Co.. Cleveland. Ohio. Houdry Products and Chemical Co.. Philadelphia. Pa.

(or regenerative air) added at the bottom of the reactor with product coming off overhead. ,The catalyst was heated to the reaction temperature in a nitrogen atmosphere. The process was carried out automatically with a make cycle (dehydrogenation) of 9 minutes and 9 minutes oxygen regeneration and repeat of the cycle. This gave a total cycle time of 18 minutes. When desired, the partial pressure of the n-butane during the reaction cycle was reduced below atmospheric by dilution with nitrogen. The total efiluent from either or both cycles was collected Dextran i s a polysaccharide of 200,000-300,000 mol. Wt. and improves the processability of the precipitate.

in an inflatable collecting device and analyzed by gas chromatography. Alternately, the effluent from the regeneration cycle was passed through a calibrated infrared analyzer to determine the amount of CO produced during regeneration (coke burn-off). By either method of analysis the amount of coke deposited on a catalyst during the reaction cycle was determined and could be taken into account when calculating the overall activity and selectivity of a catalyst. The temperatures were controlled cycle. Substantially the same analytical procedures were followed for the product gases as in an atmospheric process.

Example is according to the invention. Examples 11 and are commercial catalysts. The data shows the present catalyst to be readily comparable to both commercial catalysts. Examples 12-14 and 16-18 show the detrimental effect of aluminum added to the commercial catalysts.

TABLE II Conditions: LHSV=1.25, T =550 C. (1,022" F), Pressure=22 Hg vacuum. [9 min. reaction. Reaction cycle-590 ccJmin. of 11-04 Feed: 99 mole percent n-butaneJl min. N2 purge/9 min. regeneration. 1,500 ccJmin. of artificial air=300 ce.lmin.

Example Catalyst Total hrs. on stream 10 5/32 pellets, BeCrzOU-i-ZG wt. percent A1z(SO4)3.1SHzO 11 Houdry C, V extrusions 12 Houdry C+0.016 moles (6.7 wt. percent A12(SO4)3.18H2O 13 Houdry C+0.037 mole (14.3 wt. percent) AMSOm. 18 B 14 Houdry C+0.047 mole (17.6 wt. percent) 14126004181120 15 Harshaw CrOZllT, 5/32" dia. pellet-s 16 Harshaw Cr021l+0.016 mole (6.7 wt. percent) A12 (8093181110 17 Harshaw Cr0211+0.026 mole (10.7 wt. percent) A12(SO4)s.18HZO 18 Harshaw Cr0211+0037 mole (14.3 wt. percent) A12(SO4)1-18H2O 1 Coprecipitate oi Cr/Be=2/1 calcined at 600 C. for 1 hour in air.

by a thermoelectric temperature controller and recorded on a Leeds and Northrup 24-point recorder.

These examples demonstrate the improvement accomplished according to the present invention. The feed was 99 mole percent n-butane. The conditions and results are set out in Table I.

Examples 1 and 2 are two commercial catalyst employed in cyclic processes for dehydrogenation of butane. Example 9 is BeCr O which was pelleted and 4 through 8 are 55% (or actives deposited on a fused alumina support.

EXAMPLES 10-18 The reactor was an isothermal vacuum reactor consisting of an alonized 316 SS tube, 24 inches long and 1 inch in diameter equipped with a heating mantel and thermoelectric temperature controller. A 160 cc. bed of catalyst (112 cc. of catalyst mixed with 48 cc. of fused alumina balls) was used for each run. The reactant feed was passed down through the catalyst bed and the products removed at the bottom. The catalyst was heated to reaction temperature in a nitrogen atmosphere. The process was carried out in cycles of 9 minutes of reaction, 1 minute of nitrogen purge, 9 minutesof regeneration followed by reaction, etc. A vacuum of 22 inches of Hg was maintained during the reaction cycle and atmospheric pressure used during nitrogen purge and regeneration The invention claimed is:

1. A dehydrogenation catalyst comprising a metal chromite having a promoting amount of aluminum present in an atomic ratio of AlzCr of 0.0004 to (18:1 in

(a) a compound of the formula,

where Me is Be or Be and one or more of the divalent ions of Mg, Ca, Sr, Ba, Fe, Mn, Co, Ni, Cu, Zn, or Cd, provided that Be comprises at least 50 atomic percent of said Me ions and x is a number of from more than 0 up to 0.8; (b) an intimate mixture of metal chromite having the formula,

MeCr O where Me is Be or Be and one or more of the divalent ions of Mg, Ca, Sr, Ba, Fe, Mn, Co, Ni, Cu, Zn, or Cd provided that Be comprises at least 50 atomic percent of said Me ions and aluminum oxide; or (c) a combination of (a) and (b). 2. A dehydrogenation catalyst consisting essentially of a metal chromite having a promoting amount of aluminum present in an atomic ratio of A12Cr of 0.04 to 0.821 in a compound of the formula,

BcAl Cr O where x is a number from more than 0 up to 0.8.

3. The dehydrogenation catalyst of claim 2 wherein References Cited the atomic ratio of BezCr is 1:2.

4. The dehydrogenation catalyst according to claim 1 UNITED STATES PATENTS wherein the atomic ratio of AlzCr i 0.04 t 0,8;1, 2,342,247 2/1944 Burk 252468 X 5. The dehydrogenation catalyst according to claim 4 5 2,684,951 7/1954 Mottem 252475 wherein the aluminum is present in a compound of the 2,209,458 7/ 1940 Heard et a1 5 X f l MeA1XCr2 XO4 3,641,182 2/1972 Box, Jr. et al 260-6833 X 6. The dehydrogenation catalyst according to claim 4 2,867,578 1/ 1959 H IS hICI' 208-120 wherein the aluminum is present as aluminum oxide.

7. The dehydrogenation catalyst according to claim 4 10 CARL DEBS Pnmary Exammer wherein the aluminum is present in a combination of a US Cl XR compound of the formula MeAl Cr O4 and aluminum oxide. 252-468, 475; 260683.3

TED STAS ?ATE @FFlQE EERTEHCATE aa ceaoata Patent No 3,767,596 Dated October 23, 1973 Inventoz-(s) Harold E. Manning It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C01,. 2, line 14 reads 01? Cd" but should read or Cr Col 5 and 6, Table 1, Example Non has been omitted from Example 4.

Col 5 and 6, Table I under "Catalyst" column, reads 5 32 pellets but should read 5/32" pellets Col, 7 and 8, Table ll, under column headed C/S +S/Y+Y"', last numeral in third calculation, EX. 10 reads "3. 6" but should read N 3. 9

Col 7 and 8, Table ll, under "Catalyst" column, Example 16 reads A12 (SO2)3 but SllOUld read )3 Signed and sealed this 26th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHE'R,JR, C. MARSHALL DANN Attesting Officer Commissioner of Patents 

